RoomCoordinator: Add setup completion on start methods to fit LegacyAppDelegate calls.

Riot/Modules/Room/RoomCoordinatorProtocol.swift

@@ -29,5 +29,20 @@ protocol RoomCoordinatorDelegate: AnyObject {
 protocol RoomCoordinatorProtocol: Coordinator, Presentable, RoomIdentifiable {
     var delegate: RoomCoordinatorDelegate? { get }
     
+    // Indicate if the underlying RoomDataSource can be released
     var canReleaseRoomDataSource: Bool { get }
+    
+    /// Start the Coordinator with a setup completion.
+    /// NOTE: Completion closure has been added for legacy architecture purpose.
+    /// Remove this completion after LegacyAppDelegate refactor.
+    /// - Parameters:
+    ///   - completion: called when the RoomDataSource has finish to load.
+    func start(withCompletion completion: (() -> Void)?)
+    
+    /// Use this method when the room screen is already shown and you want to go to a specific event.
+    /// i.e User tap on push notification message for the current displayed room
+    /// - Parameters:
+    ///   - eventId: The id of the event to display.
+    ///   - completion: called when the RoomDataSource has finish to load.
+    func start(withEventId eventId: String, completion: (() -> Void)?)
 }